GB2100441A - Method for determining dimensions and/or form of surfaces - Google Patents
Method for determining dimensions and/or form of surfaces Download PDFInfo
- Publication number
- GB2100441A GB2100441A GB8118226A GB8118226A GB2100441A GB 2100441 A GB2100441 A GB 2100441A GB 8118226 A GB8118226 A GB 8118226A GB 8118226 A GB8118226 A GB 8118226A GB 2100441 A GB2100441 A GB 2100441A
- Authority
- GB
- United Kingdom
- Prior art keywords
- probe
- bore
- electrodes
- electrode
- capacitance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/28—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures
- G01B7/287—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures using a plurality of fixed, simultaneously operating transducers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/28—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures
- G01B7/281—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures for measuring contour or curvature along an axis, e.g. axial curvature of a pipeline or along a series of feeder rollers
Abstract
A non-contact method is provided for measuring the dimensions and form of an unknown surface by means of a transducer or sensor probe presented to the surface and determining the variations in capacity or electrical flux between said discrete capacitance electrode in the sensor and the adjacent unknown surface. To investigate the variations in the diameter and profile of a bore 33 a probe 30 having at least two angularly spaced capacitance electrodes 31 may be advanced along the axis of the bore and the capacitance values between each electrode and the adjoining surface measured. In another variant a single capacitative transducer probe may be moved over a surface to be measured. The probe may have an air supply duct discharging through one or more orifices adjacent the or each electrode to clean the unknown surface and (in the case of measurement within a bore) to provide a self-centering action. Several arrangements of electrodes and probes are described. <IMAGE>
Description
SPECIFICATION
Method for determining the dimensions and/or form
of surfaces
The present invention provides a non-contact
method for measuring the dimensions and/or form of surfaces by means of capacitance transducers.
In capacitance transducers one or more electrodes
are mounted so that each has an electrical capacitance to an (adjacent or) proximate electrode surface. The capacitance measured is a function of the distance of the electrode from the surface. In general
C = M Ak where C is the electrical capacitance between two parallel surfaces, area A separated by a distance d, k is the dielectric value of the ambient medium and M is a constant. If an electrode of known area A is held close to a surface, the separation of the electrode from the surface may be determined by measuring the electrical capacitance between the electrode and the surface. But capacitance transducers conventionally employ two electrode surfaces maintained in known spatial relationship.
The present invention is based on the concept of a
non-contact method for measuring the dimensional and/or form of an unknown surface by means of a transducer or sensor presented to the surface and
determining the variations in capacity or electrical flux between at least one discrete capacitance electrode in the transducer or sensor and the adjacent surface.
In some instances the body whose surface is measured may be a nonconductor in which case
use is made of its dielectric properties. The surface of the body is interposed between the transducer or sensor and a conveniently placed electrode and variations in electrical flux due to the dielectric of the body may be measured.
The range of forms which the transducer or sensor may take is considerable. It may be round, square, rectangular or any convenient shape. Usually but not necessarily the active sensing elements or capacitative electrodes will be set in a carrier which allows the elements to be transported to the position where they can sense the surface under inspection with the required accuracy and resolution. The sensor assembly, that is the electrodes set in the carrier,
may consist of sensing electrodes (each forms one capacitor plate), insulation to stop the electrode shorting to the carrier, a conductive carrier which is at an earth or some fixed potential so that all of the sensing electrodes and their connections etc, other than the required sensing surface are screened, and connections to the sensing electrodes which are led away to appropriate signal conditioning apparatus.
The nature of the electrode elements may vary considerably. They may be flush with the surface of the carrier or they may protrude or be recessed.
They can be round, rectangular or any other convenient shape such as a section of a cylinder cut at an angle. The electrodes may be adjacent to each other, separated only by insulating material or they may be set in a conductor in such a way that one probe element is screened from another.
There are two main classes of measurement using this technique.
In a first case the sensing probe has a form or shape which approximates to the shape to be measured. The surface of the probe has multiple sensing elements. Any number may be present. By measuring the capacitance from each active element of the sensor to the surface which is being measured, the shape of the unknown surface may be determined, since the shape of the sensor array is known. Thus when a round cylindrical bore isto be measured, a sensor is made which is slightly under size to the bore. Enough electrodes are inserted in the surface to give the required information. The sensor is inserted, a set of readings made, the capacitance readings converted to distance. The size of the senor is known and therefore the size of the cylindrical bore may be determined. There may be only two electrodes which are arranged at opposite ends of a diameter.Measuring first one gap and then the other will give the diameter at that one location. It is better to have 4 electrodes disposed circumferentially and spaced at 90 . One can then measure the diameter at two positions at right angles to each other which enables the ovality of the bore to be determined.
Similarly 6 or 8 electrodes would yield more information about the diameter and roundness of the bore at that location and in particular would detect higher order lobing. If the bore to be measured is fairly long then it may be desireable to measure the diameter at several axially spaced places. So axially spaced groups of circumferentially disposed electrodes can be mounted on one sensor surface to give these data. There may be two groups of two electrodes measuring the diameter at two places or there may be any number of electrode groups disposed at axial intervals along the surface of the sensor.
Measuring each gap in turn (or if desired simultaneously) allows the diameter, roundness, straightness and degree of taper of the bore to be determined.
The second method of operation involves moving a capacitative transducer probe over the surface to be measured so that the surface is sensed by the same electrode or group of electrodes. Thereby the shape of the surface may be determined from a series of measurements from the sensor rather than the one set of measurements from a static sensor. In this case it is necessary to control the movement of the probe or sensor in a known manner, the sensor is only the "fiducial" measuring element which senses small variations. The position of the probe or sensor must be measured by other means. The combination of the two measurements will then give the required shape of the profile. In one variant of this method a probe conforming to the shape of the test surface is traversed by a precision mechanism over the test surface.Thus a cylindrical probe having four electrodes can be traversed axially along a bore and at intervals along this traverse a series of groups of four readings are taken, one for each of the four electrodes disposed at 900, and each repeated at a different axial position. In this way a profile of the bore diameter, roundness, straightness can be built up by storing and assembling the data in a suitable form such as a graphic representation. In another variant the sensor probe has a limited group of electrodes disposed in a two or three dimensional array. Such a probe can be moved by an appropriate traversing mechanism so asto have the required number of degrees of freedom. These may be in rectangular or polar coordinates and may additionally provide for one or more rotational motions.
For example athree dimensional measuring machine can have a movable probe having a spherical tip the surface of which is provided with a number of capacitive sensing elements. The three dimensional machine moves the probe until the capacitance between one or more of these sensing elements reaches a predetermined value, after which the probe is moved to explore the surface under test under the control of the three dimensional measuring machine so as to maintain a constant distance from the test surface. Since the distance between the probe and the surface is held constant, the profile of the object under measurement can be determined. In the last mentioned application the probe will generally be arranged to turn one face to the surface being sensed. The turning mechanism will be on auxiliary servo drive.However, other faces of the probe need to have sensing elements in case the probe enters an area too narrow, or approaches a sharp corner and auxiliary electrodes may be provided to sense when such a condition has occurred.
Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figures 1 and 1a are schematic side and end views of a probe for measuring the surface irregularities of a cylindrical bore;
Figure 2 shows the probe of Figure 1 gauging a bore slightly largerthan itself;
Figures 3 and 3a show in side and end view a second embodiment of a cylindrical probe;
Figure4showsthe probe of Figure 3 gauging a bore of relatively large diameter;
Figure 5 shows a probe being traversed along a bore;
Figure 6 shows one circuit for measuring capacitance between a probe capacitative electrode and adjacent surface;
Figure 7 shows another circuit for measuring capacitance between a probe electrode and an adjacent surface;
Figures 8,9 and 9a show electrodes arranged in groups;;
Figure 10 shows a group of electrodes scanning a surface to be measured;
Figure 11 and 12 show arrangements in which capacitance electrodes are set in a conductive car
rier;
Figures 13 and 14 show cylindrical probes having capacitative electrodes disposed in pairs at 180 intervals and in sets of four at 90 intervals respectively;
Figures 15a-15f show spherical probes with various shapes and c''spositions of capacitative electrodes thereon.
Figure 1 shows a transducer which is intended for measurements using a probe whose surface is in a fixed attitude relative to the surface being measured and need not be moved when the surface measurement is made. In this instance a probe 30 which is a hollow cylindrical body of insulating material is being advanced axially into a hollow cylinder 33 (Figure 2) only slightly larger than itself. The geometry of the cylinder is monitored by bringing the probe into the proximity of the inner surface of cylinder 33 and measuring the capacitance between the inner surface of the cylinder and capacitative electrodes 31 which are disposed circumferentially at equi-angular intervals towards one end of the probe, heads 32 pass from respective electrodes 31 to the free end of the probe and are connected to appropriate respective capacitance measuring circuits.The capacitance between each individual electrode 31 and the adjacent surface of the cylinder can be measured with high precesion and can give an accurate measure of the distance of the respective electrode from the surface. The information derived from the individual capacitance measurements pertaining to a single annulus of electrodes 31 depends upon the number of electrodes in that annulus. Thus two electrodes disposed 180 apart can detect variations of overall bore diameter. Four electrodes disposed at 90 intervals as shown can detect whether the bore is cylindrical or elliptical. And if there are six
or more electrodes in the annulus, higherordereffects such as a lobed bore profile can be detected.
Furthermore, it may be desirable to have more than one annulus of electrodes disposed at spaced intervals along a cylindrical probe. In Figures 13 and 14 a cylindrical probe body 40 made of conductive material has capacitative electrodes 41 disposed in two axially spaced annuli, there being four electrodes in each annulus connected in pairs each 180 apart. Each electrode is insulated from the probe body40 by means of a zone on electrically insulating material 42 and leads 43 extend from the several electrodes 41 to the free end of the probe. By measuring the capacitance between the several electrodes 41 and the bore, it is possible to determine whether the axis of the probe coincides with the axis of the bore or whether it is misaligned. If there are three axially spaced annuli it becomes possible to detect whether the bore is straight or curved.
The cylindrical probe has the advantage that it can be made very compact and is useful as a free running probe typically 0.1 mm undersize for surface inspection of bores of small diameter.
A similar arrangement is shown in Figure 10 in which a probe 70 has a three dimensional array of electrodes needles embedded in an insulating substrate with their tips ground to conform to the shape
of a surface 80 to be tested. Individual electrical con
nection is made to each needle and the capacitance
between each electrode and the test surface is
measured. Variation in capacitance indicates varia
tion in spacing between the needle tip and the sur
face being tested and hence measures surface irregularities.
The shape of a surface may also be measured by means of a probe having a single sensing electrode which is moved over the entire surface to be explored by means of a suitable servo mechanism which makes a systematic traverse over the surface.
In an advantageous variant of this method onlythe direct capacitance between the sensing electrode and the surface is measured and the resulting distance information is fed back to the servo system which is arranged to maintain a constant spacing between the electrode and the surface. This is in her entiy a more accurate technique than allowing the spacing to vary. In Figure 11 a cylindrical probe has a single capacitative electrode 50 which may typically be 1 mm in diameter and is insulated from a conductive sleeve 51 by an insulating zone 52. A lead 53 extends from the electrode 50 to the free end of the probe and a surface 54 is scanned.During the scanning operation the electrode 50 should be maintained effectively normal to the adjoining region of the surface being scanned at a constant spacing therefrom of typically 0.1 mm and the associated servo mechanism may be arranged to rotate the probe to maintain it in the appropriatae attitude as scanning proceeds. The arrangement of Figure 12 is similar except that there are two electrodes 50, 50a at axially spaced locations on the probe which permix the axis of the probe to be maintained parallel to the surface being scanned.
The above surface scanning technique may also be extended to the exploration of surfaces which are curved in two or three dimensions. Where more than one electrode is present on the probe, a compensation can be made for curvature of the surface under inspection. A single plain capacitance electrode which is 1 mm in diameter and set into a metal cylinder so that the electrode is insulated from the cylinder but flush with the surface, will exhibit a certain capacitance when at a certain distance from a plane surface, say for example 0.1 mm. If that surface was curved either in one ortwo dimensions and in a sense which is convex or concave, then the capacitance of that element will change since the gap between the electrode and the surface will no longer be constant.If however there are one or more adjacent electrodes, then the manner in which the capacitance from each of these elements to the surface explored varies will be an indication that curvature is present and a suitable compensation may be incorporated into the measuring system.
In Figures 3 and 4 a relatively small probe which in this instance is of cylindrical form is being used to explore the surface of a relatively large object, in this instance a cylindrical bore whose internal diameter is considerably larger than the external diameter of the probe by being moved in a systematic pattern overthe surface of the bore by means ofatrans- ducer mechanism (not shown). A simple probe having four electrode elements disposed equi-angularly in an annulus would not give the best result and it is better to group the capacitative electrodes 35 together in a limited arc of the surface of sensing probe 36 which is rotated about its own axis so as always to offer the same face to the surface 37 being explored.A greater degree of information about the curvature of the surface being explored can be obtained by having say three, four or five electrodes and monitoring the relative response of the individual elements as the probe is traversed around the surface. Similar considerations apply to a probe being traversed so as to explore a surface geometry in three dimensions (Figure 5).
The transducer need not be of cylindrical form and in Figure 8 it is shown as a multiplicity of capacitative electrode needles disposed in a linear array and insulated from one another. Such a device may be traversed over a surface to look for non-linearity, variations of the surface from its intended dimensions, pitting and the like. Similarly in Figures 9 and 9a the capacitative electrode needles are shown grouped in bundles.
In Figures 15a-15d there is shown a generally spherical transducer probe with a multiplicity of capacitative electrodes disposed in a variety of patterns in a sector or face thereof. The spherical probe may be moved by an appropriate traversing mechanism so as to have the required number of degrees of freedom in rectangular or polar coordinates plus one or more rotational motions. For example a three dimensional measuring machine can be made to move the probe anywhere in its range of motion until the capacitance between one or more of the sensing elements and the surface reaches a predetemined value, after which the probe can be controlled by the three dimensional machine to explore the surface at a constant spacing therefrom and build up a profile of that surface.
The last mentioned application will raise several interesting items of probe design. The probe will generally turn one face to the surface being sensed.
The turning mechanism will be on auxiliary servo drive. However, it is desirable that the other faces should have sensing elements in case the probe enters an area too narrow, or approaches a sharp corner which will be sensed by the auxiliary electrode before the main electrodes. In Figure 15e the probe has three main surface sensing electrodes on one face thereof which in use is normally presented to the surface under test and auxiliary electrodes on other faces to warn of the approach of other obstacles.
Another approach is to have equal sensitivity all round as in Figure 15f so that changes in profile are sensed by different electrodes. It will be appreciated that these remarks apply as much to three dimensional sensor elements.
In addition to these features there will be times when a curved surface is being scanned. The capaci tance tance elements do not sense over zero area, and hence some errors in following may occur. Relative signals obtained from elements disposed around the surface may be used to correct for errors in following due to curvature.
In Figure 6 there is shown a circuit for measuring the capacitance between a capacitive electrode and a probe. A carrier generator supplies an output to a demodulator 61 and another output to a probe electrode which forms one plate of capacitor C1 which varies according to distance from the surface being
measured. The other plate of capacitor Cr is con
nected through fixed capacitor C2 which is in parallel with high gain amplifier 62 to the demodulator 61 or
phase sensitive detector. An output signal from the demodulator is proportional to C1/C2. In Figure 7 which shows another measuring circuit the carrier generator supplies an output two one side of transformer 65 the other winding of which is centre tapped to act as a potential divider and is connected to one plate of capacitor C1 which represents the probe and to a variable capacitor C2so as to form a bridge circuit The other plates of C1 and C supply an input to high gain amplifier 66 having parallel capacitorCi.
The value of C, may be adjusted to balance the bridge and give a nii output and in this way the value of the probe capacitance C2 can be determined.
Claims (11)
1. A non-contact method for measuring the dimensions andiorform of an unknown surface by means of a transducer or sensor probe presented to the surface and determining the variations in capacity or electrical flux between at least one discrete capacitance electrode in the transducer or sensor and the adjacent unknown surface.
2. A method according to claim 1, wherein the surface being measured is the interior of a bore and the probe is of cylindrical form and is of slightly smaller diameter than the bore and has one or more capacitative electrodes in its outer surface.
3. A method according to claim 2, which comprises measuring the capacity between the interior of the bore and two or more capacitative electrodes circumferentially spaced at equi-angular intervals in an annulus on said probe or in two or more axially spaced annuli on said probe.
4. A method according to claim 1,2 or3, wherein the body of the probe is conducting and has conductive electrodes set into it and insulated from the probe body by regions of insulating material.
5. A method according to claim 1, wherein the surface being measured isthe interior of a bore or another surface curved in two or three dimensions and the probe is substantially smaller than the diameter of the bore or the radius of curvature of the surface and is traversed over the surface.
6. A method according to claim 5, wherein one or more sensing electrodes is grouped in a limited sector of the probe, and the probe is rotated as it is scanned so as always to present the same face to the surface being scanned.
7. A method according to claim 5 or 6 wherein the probe is generally cylindrical.
8. A method according to claim 5 or 6 wherein the probe is generally spherical.
9. A method according to any of claims 5 to 8 wherein the probe is moved so as to maintain a constant spacing from the surface being scanned.
10. A method according to claim 1, wherein the probe is in the form of a three dimensional electrode array conforming to the surface being scanned.
11. A method according to claim 10, wherein the probe includes electrode needles insulated from one another with their tips ground to the shape of the surface being explored.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8118226A GB2100441A (en) | 1981-06-12 | 1981-06-12 | Method for determining dimensions and/or form of surfaces |
| EP82302938A EP0067643A3 (en) | 1981-06-12 | 1982-06-08 | Method for determining the dimensions and/or form of surfaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8118226A GB2100441A (en) | 1981-06-12 | 1981-06-12 | Method for determining dimensions and/or form of surfaces |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2100441A true GB2100441A (en) | 1982-12-22 |
Family
ID=10522485
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8118226A Withdrawn GB2100441A (en) | 1981-06-12 | 1981-06-12 | Method for determining dimensions and/or form of surfaces |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2100441A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2145231A (en) * | 1983-08-16 | 1985-03-20 | Atomic Energy Authority Uk | Capacitive gauging apparatus |
| US4644261A (en) * | 1985-02-28 | 1987-02-17 | Carter Donald L | Method of determining cylindricity and squareness |
| EP0221638A1 (en) * | 1985-08-09 | 1987-05-13 | Washington Research Foundation | Fringe field capacitive sensor and method |
| US4996492A (en) * | 1989-03-07 | 1991-02-26 | The Boeing Company | Probe for inspecting countersunk holes in conductive bodies |
| WO1992004593A1 (en) * | 1990-09-04 | 1992-03-19 | Extrude Hone Corporation | Method and apparatus for co-ordinate measuring using a capacitance probe |
| US6154972A (en) * | 1998-07-16 | 2000-12-05 | Mitutoyo Corporation | Measuring machine with cleaning device |
| EP2293011A1 (en) * | 2009-09-07 | 2011-03-09 | Siemens Aktiengesellschaft | Test device, test apparatus and test method for profile grooves |
| EP2292899A1 (en) * | 2009-09-07 | 2011-03-09 | Siemens Aktiengesellschaft | Device and method for checking profile grooves |
| WO2012154319A3 (en) * | 2011-05-09 | 2013-05-02 | The Boeing Company | Drilling machine having hole measurement capability |
-
1981
- 1981-06-12 GB GB8118226A patent/GB2100441A/en not_active Withdrawn
Cited By (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2145231A (en) * | 1983-08-16 | 1985-03-20 | Atomic Energy Authority Uk | Capacitive gauging apparatus |
| US4658254A (en) * | 1983-08-16 | 1987-04-14 | United Kingdom Atomic Energy Authority | Gauging apparatus |
| US4644261A (en) * | 1985-02-28 | 1987-02-17 | Carter Donald L | Method of determining cylindricity and squareness |
| EP0221638A1 (en) * | 1985-08-09 | 1987-05-13 | Washington Research Foundation | Fringe field capacitive sensor and method |
| US4814691A (en) * | 1985-08-09 | 1989-03-21 | Washington Research Foundation | Fringe field capacitive sensor for measuring profile of a surface |
| US4996492A (en) * | 1989-03-07 | 1991-02-26 | The Boeing Company | Probe for inspecting countersunk holes in conductive bodies |
| WO1992004593A1 (en) * | 1990-09-04 | 1992-03-19 | Extrude Hone Corporation | Method and apparatus for co-ordinate measuring using a capacitance probe |
| AU645951B2 (en) * | 1990-09-04 | 1994-01-27 | Ex One Corporation | Method and apparatus for co-ordinate measuring using a capacitance probe |
| US6154972A (en) * | 1998-07-16 | 2000-12-05 | Mitutoyo Corporation | Measuring machine with cleaning device |
| EP2292899A1 (en) * | 2009-09-07 | 2011-03-09 | Siemens Aktiengesellschaft | Device and method for checking profile grooves |
| EP2293011A1 (en) * | 2009-09-07 | 2011-03-09 | Siemens Aktiengesellschaft | Test device, test apparatus and test method for profile grooves |
| WO2011026973A1 (en) * | 2009-09-07 | 2011-03-10 | Siemens Aktiengesellschaft | Method and device for testing profiled grooves |
| WO2011026974A1 (en) * | 2009-09-07 | 2011-03-10 | Siemens Aktiengesellschaft | Test device, test apparatus and test method for profiled grooves |
| CN102483325A (en) * | 2009-09-07 | 2012-05-30 | 西门子公司 | Test Device, Test Apparatus And Test Method For Profile Grooves |
| CN102498263A (en) * | 2009-09-07 | 2012-06-13 | 西门子公司 | Method and device for testing profiled grooves |
| WO2012154319A3 (en) * | 2011-05-09 | 2013-05-02 | The Boeing Company | Drilling machine having hole measurement capability |
| CN103517783A (en) * | 2011-05-09 | 2014-01-15 | 波音公司 | Drilling machine having hole measurement capability |
| JP2014516811A (en) * | 2011-05-09 | 2014-07-17 | ザ・ボーイング・カンパニー | Drilling machine with hole measuring function |
| US9199351B2 (en) | 2011-05-09 | 2015-12-01 | The Boeing Company | Drilling machine having hole measurement capability |
| CN103517783B (en) * | 2011-05-09 | 2017-05-24 | 波音公司 | Drilling machine having hole measurement capability |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |